Changes in Nutritional Properties and Bioactive Compounds in Cereals During Extrusion Cooking

Abstract

Maintaining and improving the nutritional quality of foods during processing are the main market and industry concerns. Thus, research should focus on novel and sustainable ways for selecting the appropriate processing method that either increases or does not affect the nutrient content of foods. Thermal processing techniques such as extrusion cooking are widely used for producing breakfast cereals, snack foods, pasta, pet food, etc. Extrusion cooking is a continuous process that uses a combination of high-temperature, highpressure, and high shear conditions in a short period of time, which results in molecular transformation and chemical reactions within the extruded products. Extrusion cooking brings on many biochemical changes such as denaturation of proteins, gelatinization of starch, lipid modifications, inactivation of microorganisms and enzymes, formation of volatile flavor components, and increase in soluble dietary fiber. Furthermore, extrusion cooking has the potential to improve the nutritional quality of the products by improving starch and protein digestibility and increasing the retention of bioactive compounds with antioxidant properties. Also, this highly efficient technology minimizes water pollution and energy consumption. This review aims to discuss the current information regarding changes in nutritional properties and bioactive compounds in cereals processed by extrusion cooking.

Feed rate, water addition rate and mixture composition nexus role on alterations of nutritional properties in extrusion of composites containing rice ( Oryza sativa ), sorghum [ Sorghum bicolor ), and bamboo ( Yushania alpina ) shoots

“…These processes alter among significantly the nutritional constituents. This culminates in having a product that has improved nutritional properties than in the raw materials due to significant reduction of anti‐nutrients and increased digestibility (Moreno et al., 2017; Offiah et al, 2018). According to Lillford (2008), the composition and properties of the extruder feed material is very vital to the entire process of transformation.…”

Extrusion and nixtamalization conditions influence the magnitude of change in the nutrients and bioactive components of cereals and legumes

“…During extrusion and nixtamalization, many chemical changes occur that affect the chemical and nutritional composition of processed foods as summarized on Table . These changes include denaturation of protein, gelatinization of starch, formation of volatile flavors, increase in soluble fibers, and inactivation enzymes (Moreno et al, ). While the high temperature short time method used in cooking can preserve nutrients, denature antinutritional factors, and therefore increase protein digestibility compared to conventional cooking (Moreno et al, ), it may also decrease some bioactive compounds making extruded products low in β ‐carotene, tocopherols, and phenolic acids and may promote Maillard browning that leads to reduction in lysine, an essential amino acid thereby reducing both the quality and quantity of protein (Hurrell, ).…”

“…Extrusion helps disrupt the food matrix and make phytochemicals more bioaccessible (Ti et al, ) through increased gelatinization of starch, denaturation of protein that bind these phytochemicals, and breaking down of many complexes in which these compounds are embedded or entrapped (Wolfe & Liu, ). Since extrusion increases extractable amount of phytochemicals which may also be used as a proxy for increased bioaccessibility, it is not surprising that extruded rice displayed high oxygen radical absorbance capacity (ORAC) (Ti et al, ) because of not only increased availability of radical scavenging phytochemicals but also due to compounds formed during Maillard browning reactions that have antioxidant effect (Moreno, Fernandez, Rodriguez, Carrillo, & Rochin, ). The decrease in bound phenolics and increase in free phenolics observed after extrusion of rice (Ti et al, ) supports this notion.…”

Bio-Functional and Structural Properties of Pasta Enriched with a Debranning Fraction from Purple Wheat

“…The data in Table 2 indicate an apparent decrease in both TAC and TPC in uncooked pasta samples with respect to what expected from the mixing formula. Losses in either family of phenolics may have occurred in the pasta-making process (most likely as a consequence of the drying steps in pasta production [7,31,32]), but the observed decrease may also be attributed to difficulties in recovering either species from the highly structured protein matrix formed upon kneading and drying.…”